Previous methods of detoning carrier involved passing toned carrier through a ceramic lined air classifier. This device was used for ferrite carrier detoning and was decommissioned several years ago then disposed. A need for a relatively inexpensive detoning apparatus has arisen to allow separation of toner from carrier in reclamation and other facilities.
Embodiments comprise a target and an inlet thmugh which toner laden carrier enters the apparatus and can strike the target. The target can be, for example, a 4″ to 6″ metal disc target offset 1″ to 2″ from the center of a screen filter. The apparatus also includes an exit through which detoned carrier passes and an exit through which separated toner passes. The carrier exit can be located below the target, whereas the detoned carrier will be located downstream of the target. This arrangement efficiently loosens toner attached to air entrained carrier, and at the same time protects the fine wire screen filter of the toner separation apparatus from direct impact of the high density carrier.
The apparatus can also include a filter downstream of the target through which toner can pass. The preferred filter medium is, for example, a woven fine wire cloth type. A mesh to which the target is attached can be located between the inlet and the filter and should be sized so that both toner and carrier can pass through the mesh. Preferably, the mesh is made from a rigid, heavy gauge sheet metal with large perforations.
The toner-laden carrier can be entrained by air driven by an impeller. The impeller can be located within the apparatus, upstream or downstream of the target. For heavier developers, embodiments can employ an air entrainment device to enable transport and efficient entrainment of the developer. For example, the impeller could be mounted in the inlet or in the toner exit. Alternatively, the impeller can be located external to the apparatus and be in fluid communication with the apparatus, such as in a duct or the like attached to the toner exit. In embodiments, a plurality of impellers can be employed in various locations to enhance flow of toner-laden carrier and the separated toner and carrier particles.
A feature of embodiments is the steep, up to 90 degree, angle to the incoming air entrained carrier stream and the offset from the screen surface which allows the approximately 1–20 micron toner to de-attach itself from the approximately 40–150 micron carrier and be carried in the air stream through the fine mesh screen filter (approximately 25 to 45 micron opening size). The offset of the target from the inlet allows the air flow stream patterns to efficiently entrain the loose toner through the screen filter while the carrier falls by gravity along the screen filter surface to a collection vessel.
The apparatus executes a detoning or toner separation method including providing a supply of toner laden carrier, providing a target, providing a filter, and providing an impeller. The method can further comprise providing a mesh to which the target is attached, and providing a filter through which the toner can pass, the filter being attached to the door. The mesh with the attached target is held in place by brackets attached to the inside of the conical door. The method can also include providing a sweeper bar that agitates material on the filter, which prevents the filter from clogging. Advantageously, the method can further include providing a carrier exit through which detoned carrier travels and/or providing a toner exit through which the separated toner passes.
Embodiments have been employed to detoned an incorrect toner (8% toner concentration, TC) from developer so that the carrier could be reclaimed and developer blended with the proper toner. The toner needed to be removed down to a 0.1% TC to assure against detrimental toner contamination. A slightly conical disc target was centered as a perpendicular impact target a short distance from the screen filter surface. The entire air entrained developer stream impacted the target. A single pass at high developer flow rate (approx. 500 lbs/hr) detoned the carrier to 0.4% TC from the starting 8% TC. With the target, over 10,000 lbs. was processed without screen damage. A second pass reduced the TC further to 0.1% TC (a low acceptable toner contamination TC).